Bulletin of the Seismological Society of America; December 1974; v. 64; no. 6;
p. 1707-1713
© 1974 Seismological Society of America
Dilatancy and spatial distribution of aftershocks
INDRA N. GUPTA
MACKAY SCHOOL OF MINES UNIVERSITY OF NEVADA, RENO, NEVADA 89507
Abstract
The pre-earthquake dilatancy, postulated to explain certain premonitory seismic velocity changes, may provide a preferred direction of groundwater flow persisting after the occurrence of a shallow earthquake. This direction is parallel to and nearly coincident with the compressive stress axis associated with the focal mechanism of the principal shock. Aftershocks may result from a redistribution of pore pressure and fluid flow not only along faults but also along this direction of relatively large permeability. This suggestion provides a possible explanation for certain observations of aftershocks aligned along the compressive stress direction.
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